GB2529692A

GB2529692A - Turbine assembly

Info

Publication number: GB2529692A
Application number: GB1415335.7A
Authority: GB
Inventors: Luke Neil Mcewen
Original assignee: Gurit UK Ltd
Current assignee: Gurit UK Ltd
Priority date: 2014-08-29
Filing date: 2014-08-29
Publication date: 2016-03-02
Also published as: WO2016030431A1; EP3186503A1; GB201415335D0

Abstract

A turbine assembly comprising a turbine blade, a turbine member and a mounting assembly; wherein the turbine blade comprises a root mounting portion having a wall and a hole extending through a thickness of the wall, the hole being partially defined by an engagement surface facing away from a root end of the turbine blade; wherein the mounting assembly comprises a peg and a clamping member, the clamping member being coupled to the turbine member; wherein the peg extends through the hole and comprises fist and second opposed bearing surfaces, the first bearing surface engaging a clamping surface of the clamping member and the second bearing surface engaging the engagement surface of the hole. A kit of parts for a turbine assembly and a method for assembling a turbine assembly are disclosed.

Description

TURBINE ASSEMBLY

The present invention relates to a turbine assembly, a kit of part.s for a turbine assemhy and a method of assembling a turbine assembly. The present invention relates particularly to turbines for tidal generators.

Wind and tidal turbine blades are typically formed of laminated composite material (for fatigue resistance), bolted to the turbine huh using steel bolts, A connection therefore needs to be made between the bolts and the composite blade, Tidal hubs are usually sealed, and hence there is no access inside the hub for tightening the nuts on the blade connecting bolts.

Small wind turbines also have limited or no manual access due to the size of the hub.

There are a number of known techniques to affix such blades.

In one known technique, each hub spindle includes an enlarged circumferential flange to which the blade root is affixed using Tbol1s. However, that structure exhibits the problem of poor hydrodynamics. There are further prohkms in that despite a heavy and expensive spindle, the spindle is susceptible to fatigue failure at the internal radius of the flange.

in another known technique, the hEade root incorporates a radially outwardly directed circumferential flange, and studs are screwed into blind holes in a hub spindle. Nuts are fitted onto the outboard end of the studs. This arrangement suffers from the problem that the tianges are not strong enough when fabricated from fibre rein.thrced resin matrix composite material due to through thickness tensile (Brazier) loads at the tight radius, and so the flange tends to be made in steel or spheroidal graphite iron (SO!), which then needs to he connected to the composite blade, typically by an adhesive joint. The difference in stifthess between the composite material and steel/SO! can lead to the existence of stress concentrations in the adhesive joint. This in turn can result in a problem of the lowering of the fatigue resistance of the adhesive, particularly when subjected to underwater enviromnents.

There is therefore a need for an improved coupling between turbine blades and a huh that improves performance and reliability, and which reduces the cost and complexity of manufacture and assembly.

A first aspect of the invention provides a nfrhi.ne assembly according to claiiri 1.

A second aspect of the invention provides a kit of parts fbr a turbine assembly according to claim 39. A kit of parts according to the second aspect of the invention may be used to form a turbine assembly according to the first aspect of the invention. The kit of parts may therefore include any of the features described in relation to the first aspect of the invention.

A third aspect of the invention provides a method of assembling a turbine assembly according to claim 44.

Preferred features are defined in the dependent claims.

Embodiments of the present invention will now be described by way of example only with reference to the accompanylng drawings, in which: Figure 1 shows a schematic front view of a turbine; Figure 2 shows a schematic front view of a root mounting portion of a turbine blade having a turbine assembly according to one embodiment of the present invention; Figure 3 shoes a schematic cross-section of the root mounting portion shown in Figure 2; Figure 4 shows a more detailed view of a portion of the schematic cross-section of Figure 3; Figure 5 shows a schematic exemplary interface between a turbine member and a root mounting portion of a turbine blade; Figure 6 shows a schematic perspective view of a peg used in one embodiment of the present invention, and Figure 7 shoes a schematic cross-section of a portion of a root mounting portion of a turbine blade having a turbine assembly according to another embodiment of the present invention.

Figure 1 shows a tidal water-driven turbine I having a rotatable hub 2 with two turbine blades 3 mounted to the hub. In other embodiments the turbine may be any other turbine, especially a water-driven or air-driven turbine, having any number of blades.

Each turbine blade 3 is coupled to a respective turbine member 4 which is in turn coupled to a main body of the hub 2 by a mounting arrangement 8. Each turbine member 4 is generally cylindrical, as shown in Figures 3 and 5, although other configurations are possible. The turbine members 4 are manufactured separately from the main body of the hub 2 to simplify the manufacture of the huh. in other embodiments the turbine blades may be coupled directly to the hub such that the hub or a portion of the hub acts as a turbine member as described below. The hub 2 and the turbine members 4 are typically composed of a metal.

Each turbine blade 3 includes a root mounting portion 3a at a proximal end for coupling the turbine blade to its respective turbine member 4, and a main body portion 3b located outboard of the root mounting portion and extendng outwardly to a tip 3c. Each root mounting poi.'tiun 3a includes a wail 100 which extends in a continuous, substantially circular closed loop, as shown in Figures 3. 4, 5. In other embodimerts the wall may be elliptical or have any other shape, and may not form a closed, loop.

The wall 100 includes an end mounting surface I QUa which engages a complementary mounting surface 4a of the turbine member 4. The end mounting surface I QUa is inclined at an angle to a plane extending transversely to a longitudinal axis 9 of the root mounting portion 3a. The angle is preferably an acute angle, more preferably between 2° and 30°, and most preferably between 5° and I 0°. As shown in Figure 5, the end mounting surface iOOa is upwardly and outwardly tapered such that a radially outer edge is further towards the tip end 3c of the turbine blade than a radially inner edge In other embodiments the end mounting surface may be downwardly and outwardly tapered such that a radially inner edge is further towards the tip end. In other embodiments the end mounting surface lUQa and complementary mounting surface 4a may be substantially planar or have some other shape.

In other embodiments a locating spigot may be provided which engages an inner surface of the wafl IOU. In other embodiments there may he one or more intervening components between the end mounting surface lOOa and the complementary mounting surface 4a, for

example a seaL

The wall 100 extends away from the end mounting surface I UCla towards the tip end 3c of the turbine blade 3 at an acute angle to the longitudinal axis 9 of the root mounting portion 3a, such that the root mounting portion 3a tapers inwardly away from the end mounting surface.

A taper is particularly desirable in waterdriven turbines to reduce drag. & taper commencing from the root end is desirable to minimise drag and reduce or eliminate the need for a double curvature, Tn other embodiments the taper may commence from a point outboard of the end mounting surface IOOa (but preferably between the end mounting surface and the hole 101.

described below), or alternatively the root mounting portion may not he tapered inwardly.

The turbine blades 3 are typically composed. of reinforced composite material, for example laminated layers of tihrereinforeed polymer formed using prepreg or resin.-infused plies.

although the other materials may be used. Typically at least some of the laminated layers of reinforcement extend continuously out from the root mounting portion 3a into the main body portion 3b at the turbine blades 3.

The wall 1(X) of each root mounting portion 3a has four holes 101 extending through a thickness of the wail, although a different number of holes is possible as will become clear front the following description. The h.&es 1.01 are spaced apart along a width direction of the wall 100 and each hole is partially detined by an engagement surface 102 facing away from the end mounting surface lOOn of the turbine blade. In other embodiments the number of holes 101 may he significantly greater. for example at least 10 or at least 20 or at least 30 or at least 40. in one particular prefened embodiment the number of holes is 34.

Each turbine blade 3 is coupled to its respective turbine member 4 by a. turbine assembly 5 as shown in Figure 2 and in crosssection in Figure 3. The c.ouphng of one of the turbine blades 3 to its respective turbine member 4 will now be described, although it will be understood that both turbine blades are coupked to their respective turbine members using similar turbine assemblies.

The turbine assembly 5 includes the root mounting portion 3a of the turbine blade 3, the turbine member 4 and four mounting assemblies 10. Each of the mounting assemblies corresponds to a respective one of the four holes 101 through the wall 100. In other embodiments any other number of holes and corresponding mounting assemblies may be used. including one.

The mounting assembly 10 includes a peg 200, a clamping member 300 and a retaining member 400. The following description generally refers to a single mounting assembly 10, shown in detail in Figure 4, although it will be understood that each of the mounting assemblies are arranged and fimction in a similar manner.

The peg 200 extends through the hole 101 and has first 201 and second 202 opposed hearing surfaces, The term "opposed bearing surfaces" means bearing surthees which generally face in different directions, and includes hearing surfaces which are laterally offset from each other instead of directly opposed, and which are angled with respect to each other instead of parallel as shown in Figure 4.

The second bearing surface 202 engages the engagement surface 102 of the hole 101 The second hearing surface 202 and the engagement surface 102 are curved with curvature about a longitudinal axis of the peg. An intert cc between the second bearing surface 202 and the engagement surface i 02 is therefbre ardhed, The complementary curved surfaces of the peg and the wall need not be exactly aligned with the ongitudinaI axis of the peg. in other embodiments these complementary bearing surfaces may be part spherical (with curvature in two directions) or substantially planar or any other shape.

The first bearing surface 201 engages a clamping surface 303 of the clamping member 300 (which is described below), The first bearing surface 201 and the clamping surface 303 are also curved with curvature about a longitudinal axis of the peg An interface between the first hearing surface 201 and the ckmping surface 303 is therefore arched. The complemental)' curved surfaces of the peg and the clamping member need not be exactly aligned with the longitudinal axis of the peg. In other embodiments these complementary hearing surfaces may be part spherical (with curvature in two directions) ot' substantially planar or any other shape. In any case, the first bearing surface and the clamping surface are substantially continuous bearing surfaces and may be moved towards each other into engagement or out of engagement and away from each other when not constrained by other components. The movement rna.y be in a direction normal to the interface between the first bearing surface and the clamping surface and/or in a direction parallel to the interface.

The peg 200 also has a bore 203 extending through its height in a direction generally towards the turbine member 4, as shown in Figure 6. The bore 203 is for receiving a stud 401 of a retaining member 400 (described below), in other embodiments there may he miJtipie bores for receiving multiple studs, in other embodiments the bore(s) may be replaced by one or more open notches or grooves configured to engage a portion of a retaining member. In other embodiments a bore/notch/groove may not he required.

The peg 200 comprises a taper with an increasing dimension from a first end 200a located towards the clamping member 300 to a second end 200b located towards the retaining member 400 (which is described. below). The taper increases the height of the peg 200 in a direction aligned with the longitudinal axis 9 of the root mounting portion 3a. I'he hole 10! in the wall 100 is straight sided, as shown in Figure 4. but in other embodiments may have a corresponding tapered shape. The taper allows manufacturing tolerances to be compensated thr during assembly of the turbine i by pushing the peg 200 fhrther into the hole 101. The ) bore 203 through the peg 200 is preferably enkarged compared to the stud which passes through it (as described h&ow) and/or slotted with an increased dimension in a direction aligned with the longitudinal axis of the peg to allow for positional adjustment of the peg with respect to the hole 101. Alternatively or additionally. the peg may be tapered in a wdth direction of the peg which is perpendicular to the longitudinal axis of the root mounting portion and perpendicular to a longitudinal axis of the peg. Again, the hole in the wall may or may not have a corresponding tapered shapeS in other embodiments the peg may not be tapered.

The peg 200 is taller in the height direction than the ridfl direction to improve its bending strength in its primary load carrying direction. The hole 101 in the waIl IOU is correspondingly taller (in a direction aligned with the longitudinal axis 9 of the root mounting portion 3a) than it is wide (in a direction perpendicular to the longitudinal axis of the root mounting portion and parallel to the width direction of the wail) to reduce the required hole width. The peg 200 and the hole 100 may have a substantially oval shape or alternatively any other shape.

The clamping member 300 is spaced apart from the wall 100 on a first side of the wall, The clamping member 300 is located on an inside of the closed loop formed by the wall 100. The clamping member 300 comprises an annular wail 30! within the closed ioop. the wall extending around the inside of the root mounting portion 3a, The annular wall 301 may be, for example, cylindrical or I ustoconical in shape.

The clamping member 300 has a plurality of holes 302 extending through the thickness of its annular wall 301, each hole corresponding to a respective one of the mounting assemblies 1 0 and providing a clamping surface 303 facing generally towards the turbine member 4. in other embodiments the clamping surfaces 303 may he provided by recesses andIor overhanging portions (as shown in Figure 7) instead of holes. In each case the clamping surface 303 is preferably fonned in the wall 301 or on a portion of the clamping member which is integrally formed with the wail or otherwise rigidly fixed to the tvall. In other embodiments multiple clamping members may be provided, each providing clamping surface(s) for one or more of the mounting assemblies 10 instead of a single clamping member providing clamping surfaces for all of the mounting assemblies, and the clamping member may not be annular. *1'

The clamping surface 303 is curved. As described above with reference to the peg 200, the damping surface 303 has curvature about a longitudinal axis of the peg (as does the first clamping surface of the peg).

As shown in Figure 4, the clamping surface 303 extends in a direction away from the longft-udin& axis 9 of the root mounting portion 3a and towards the wall 100 of the root mounting portion, and is generally inclined at an acute angle to a plane extending LraEIsversely to the longitudinal axis of the root mounting portion. The clamping surface 303 is inclined inwardy towards a centre of the root mounting portion and downwardly away fl-urn the tip end 3c of the turbine hade 3 such that an innermost portion of the clamping surface (with respect to the clamping member) is located, further away from the tip of the turbine blade and further towards the turbine member 4 than an outermosr portion of the clamping surface.

The clamping member 300 has an annular projecting portion 304 providing a second clamping surface 305 opposing the first clamping surface 303. The second clamping surface 305 is located on an opposite side of the turbine member 4 to the first clamping surface 303, and engages an underside of the turbine member 4 to couple the clamping member to the turbine member. The clamping member 300 is held in position by the forces transferred between the clamping member 300 and the peg 200, as described below. In other embodiments the second clamping surface 305 may not he provided by annular ring 304 but by one or more projections and/or recesses. Alternatively, or additionally, the clamping member 300 may he coupked to the turbine member 4 in some other way, for example by one or more mechanical ihsteners and/or other interlocking features. In other embodiments the clamping member 300 may be integrally formed with the turbine member 4, as shown in Figure 7.

The retaining member 400 is spaced apart from the wall and. is located on the outside of the oop formed by the wall 100 (that is on the opposite side of the vail to the clamping member 300). The retaining member 400 includes a stud 401 passing through the bore 203 in the peg and a nut 402 coupled to a threaded portion of the stud. The nut 402 bears against a.

portion of the peg 200 located on the same side as the first hearing surface 201 and opposite the second bearing surface 202. As can be seen in Figures 3 and 4, the retaining member 400 and clamping member 300 engage the peg 200 at opposite end portions of the peg.

The stud 401 may further include a second threaded portion for coupling the stud to the turbine member. In other embodiments there may he multiple studs passing through one or more bores through each peg. In other embodiments the retaining member may take some other form, for example a component having a bearing surface theing generally towards the turbine member which engages the neg.

The first clamping surface 303 of the clamping member 300 engages the first bearing surface 201 of the peg 200, and the clamping member transfers a first force to the peg in a first direction 1001 towards the tutbine member 4, as shown in Figure 6. The nut 402 of the retaining member 400 engages the peg 200 and the retaining member transfers a second force to the peg in a second direction 1002 towards tite turbine member 4. The second bearing surface 202 of the peg 200 engages the engagement surface 102 of the hole 10!, thereby transferring a third force to the root mounting portion 3a of the turbine blades 3 in a third direction 1003 towards the turbine member 4. In this way, the peg 200 urges the root mounting portion 3a into engagement with the turbine member 4 and pre1oads the root mounting portion in compression, thereby retaining the turbine blade 3 on the turbine member, The first, second. and third directions may each he angled with respect to each other, as shown in Figure 4, hut in other embodiments may he substantially paraflel, as shown in Figure 7.

The nut 402 of the retaining member 400 is adjtstabe along the threaded portion of the stud 401 towards and away from the turbine member 4. The retaining member 400 may thereibre he tightened to increase the pre4oads in the root mounting portion 3a and in the retaining member. and loosened to reduce the pre-loads.

The location at which the clamping member 300 engage.s the peg 200 is separated from the location at which the peg 200 engages the wall 100 by a first distance A. and the location at which the peg 200 engages the wail 100 is separated from the location at. which the retaining member 400 engages the peg 200 by a second distance B, as shown in Figure 6. Th.e second distance B is greater than the first distance A such that the clamping rrenther 300 carries a greater load than the retaining member 400, thereby reducing the loading of the retaining member such that smaller diameter studs and/or fewer mounting assembhes are required. In other embodiments the distance A may be greater than the distance B or the distances A and B may be substantially equal The engagement surface 102 of the hole 1 01 and the complementary second bearing surthee 202 of the peg 200 are substantially perpendicular to the wail 100 at the location of the hole, such that the force transferred from the peg to the wall is aflgned with the direction of the wail. For a wall made from composite layers this is advantageous in order to avoid through thickness stresses in the wail. in other embodiments these complementary hearing surfaces may not be substantially per endicular to the wall.

The engagement surface 102 of the hole 101 and the complementary second hearing surtlce 202 of the peg 200 are inclined at an acute angle to a plane extending transversely to the direction 1002 of the force transmitted to the peg by the retaining member (which is aligned with the longitudinal direction of the stud 401). The thrce transmitted to the peg 300 by the retaining member 400 therefore acts to urge the peg inwardly into the hole 101, resisting any tendency of the taper angle of the peg to push the peg outwards. Ihe engagement surface 102 of the hole 10! and the comolementary second bearing surf: cc 202 of the peg 200 are a!so inclined at an acute angle to the first bearing surface 201 of the peg and the first clamping surthce 303 of the clamping member 300. in other emnbodmnerits the engagement surface 102 of the hole 101 and the complementary second bearing surface 202 of the peg 200 may be substantially perpendicular to the force transmitted to the peg by the retaining member 400 and/or substantially parallel to the first bearing surface 201 of the peg 200 and the first clamping surface 303 of the clamping member 300, as shown in Figure 7.

Thc turbine assembly is assembled by the tuliowing steps: a, Couple the clamping member 300 to the turbine member 4 (this step is ehminated in embodiments where the clamping member is integrally formed with the turbine member); b. Position th.e foot mounting portion 3a with respect to the turbine member 4 with the end mounting surthce I OOa. engaging the complementary mounting surface 4a; c. Insert the pegs 200 through the holes 101 until the first hearing surfaces 201 engage the clamping surfaces 303 and the second bearing surfaces 202 engage the engagement. surfaces 102; d, !nsert. the studs 401 through the bores 203 formed in the pegs 200 and couple the studs to the turbine member 4; 0* e. Thread the nuts 402 onto the studs sun tighten the nuts onto the upper surfaces of the pegs 200. thereby securing the root mounting portion 3a to the turbine member 4 and proloading the root mounting portion in compression; ±1 Adjust the nuts 402 to generate the required preioads in the studs 401 and. in the root mounting portion 3a, The skilled person will appreciate that the above steps need not he carried out in the order in which they are presented. For example, one or more pegs 200 may be inserted through the holes 101 bef re the root mounting portion 3a is positioned relative to the turbine member 4.

The turbine assembly may be disassembled by reversing the above steps.

The root mounting portion 3a, turbine member 4 and mounting assembly 5 are arranged such that th.e peg 200 may be inserted through the hole 101, the first bearing surface 201 brought into engagement with the clamping surface 303 and the second bearing surthee 202 brought into engagement with the engagement portion 102 and th.e assembly secured together without requiring access to the side of the wall 1 00 on which. the clamping member 300 is located.

Therefore the turbine assembly and method described above do not require access to the inside of the root mounting portion 3a or the inside of the turbine huh 2 when assembling, adjusting and disassembling the turbine assembly, thereby increasing the ease and reducing the cost of erecting, maintaining and decommissioning of the turbine 1.

[he clamping surface 303 of the clamping member 300 and the first bearing surface 201 of the peg 200 are arranged to allow relative movement between the peg and the clamping member in an axial direction of the peg. Relative movement between the peg 200 and the clamping member 300 is substantially prevented by friction at the mating surfaces when the turbtne assembly is fully assembled with the retaining members 400 tightened. However, if the retaining members 400 are loosened to reduce or eliminate the loading at the bearing surfaces, the peg may be adjusted in its axial direction, This may he done, for example, during assentbiv, maintenance or disassembly of the turbine. The movement may he sliding movement while second bearing surface 2'Oi remains in contact with the clamping surface 300. or alternatively the second bearing surface may be moved apart from the clamping surface before or during axial movement of the peg.

Preferably the peg 200 is not attached directly to the clamping member 300 by any mechanical fasteners or interlocking features so that it can be readily moved relative to the clamping member during assembly, maintenance and disassembly of the turbine assembly without requiring access to the inside of the loop tbrmed by the wall 1(30 (that is the side of the wall on which the clamping member 300 is located). In other embodiments one or more mechanical fasteners and/or interlocking features may be employed at the interface between the clamping surface 303 and the first bearing surface 201 of the peg.

Various other modifications will be apparent to those skilled in the art. 11:

Claims

CLAIMSI, A turbine assembly comprising a turbine blade, a turbine member and a mounting assembly; wherein the turbine blade comprises a root mounting portion Ii aving a wall and a hole extending through a thickness of the wall, the hole being partially defined by an engagement surface facing away horn a root end at' the turbine blade; wherein the mounting assembly comprises a peg, a clamping member and a retaining member: the clamping member and the retaining member being located or opposite sides of the wall; wherein the damping member and the retaining member are respectively coupled to the turbine member and respectively coupled to opposite end portions of the peg; wherein the peg extends through the hole and comprises first and second opposed hearing surfaces, the first bearing surface engaging a clamping surface of the cLamping member and the second hearing surface engaging the engagement surhice of the hole.
2. A turbine assembly according to claim 1, wherein the wail extends in a closed loop
3. A turbine assembly according to claim 2, wherein the clamping member is located on an inside of the dosed loon fbrmed by the wall.
4. A turbine assembly according to claim 3. wherein the clamping member comprises an annular wall within the closed oop formed by the wall of the root mounting portion.
5. A turbine assembly according to any preceding claim, wherein the clamping surface extends in a direction away from a longitudinal axis of the root mounting portion and towards the wall of the root mounting portion.
6, A turbine assembly according to any preceding claim, wherein the clamping surface is generally inclined at an acute angle to a plane extending transversely to a longitudinal axis of the root mounting portion.
7. A turbine assembly according to claim 6. wherein the clamping surface is inclined inwardly towards a centre of the root mounting portion and downwardly away from a tip end of the turbine blade.
8. A turbine assembly according to any precedin.g dairn, wherein an interface between the clamping surface and the first hearing surface of the peg is free of any interlocking features.
9, A turbine assembly according to any preceding claim, wherein an interface between the clamping surface and the first heating surface of the peg is free of any mechanical thsteners,
10. A turbine assembly according to any preceding claim, wherein the clamping surface and the first bearing surface allow relative movement between the peg and the clamping member in an axial direction of the peg.
II. A turbine assembly according to any preceding claim, wherein the clamping surface and the first hearing surf ice may he moved towards each other into engagement or out of engagement and away front each other.
1 2. A turbine assembly according to any preceding claim, wherein an interfiice between the clamping surface and the first. bearing surface is curved.
13. A. turbine assembly according to claim 12, wherein the clamping surface is curved about a longitudinal axis of the peg.
14. A turbine assembly according to claim 13, wherein the first hearing surface has a curvature which corresponds to the curvature of the clamping surface.
15. A turbine assembly according to any preceding claim, wherein the clamping member is formed as a separate part to the turbine member.
16. A turbine assembly according to claim 15, wherein the clamping member further comprises a second clamping surface opposing the first clamping surface, wherein the second clamping surface engages the turbine member to thereby coupe the clamping member to the turbine member.
17. A turbine assembly according to any preceding claim, wherein the retaining member transmits a force to the peg in a direction towards the turbine member.
18. A turbine assembly according to claim 17. wherein the retaining member is adjustable in a direction towards the turbine member,
19. A turbine assembly according to claim 17 or 18. wherein the retaining member comprises a stud passing through a bore in the peg.
20. A turbine assembly according to claim 19, wherein the bore is enlarged compared to the stud and/or slotted with an increased dimension in a direction aligned with a longitudinal direction of the peg.
21. A turbine assembly according to claim 19 or 20, wherein the stud includes a helically threaded portion, wherein the retaining member further comprises an annular member having a complementary helically threaded portion coupled to the helically threaded portion of the stud, the annular member bearing against a surface of the peg.22. .A turbine assenthiy according to any of claims 17 to 21, wherein the location at which the clamping member engages the peg is separated from the location at which the peg engages the tvail by a first distance, and the location at. which the peg engages the wall is separated from the location at which the retaining meniber engages the peg by a second distance, the second. distance being greater than the first distance.23. A turbine assembly according to any of claims 17 to 22, wherein the second hearing surthce of the peg is inclined at an acute angle to a plane extending transversely to the direction of the force transmitted to the peg by the retaining member.24. A turbine assembly according to any preceding claim, wherein the secondbearing surface of the peg is inclined at an acute angle to the first hearing surface, 25. A turbine assembly according to any preceding claim, wherein, the second bearing surface of the peg is substantially perpendicular to the wail at the location of the ho!e.26. A turbine assembly according to any preceding claim., wherein the second bearing surface of the peg is curved shout a. longitudinal axis of the peg.27, A turbine assembly according to any preceding claim, wherein the peg is taller in a direction aligned with a longitudinal axis of the root mounting portion ib an it is wide in a direction perpendicular to the longitudinal axis of the root mounting portion and to a longitudinal direction of the peg.28. A turbine assembly according to any preceding claim, wherein the peg comprises a first end located on a first side of the wall and a second end located on. a second side of the wall, wherein the peg comprises a taper with an increasing dimension from the first end towards the second end.29. A turbine assembly according to any preceding claim, wherein the root mounting portion comprises an end mounting surface engaging a complementary mounting surface of the turbine member.30, A turbine assembly according to claim 29. wherein the vai1 extends away from the end mounting surface towards a tip end of the turbine blade at an acute angle to a longitudinal axis of the root mounting portion.3 I. A turbine assembly according to claim 29 or 30, wherein the end mounting surface is inclined at an angle to a plane extending transversely to a longitudinal axis of the root mounting portion.32. A turbine assembly according to any preceding claim, wherein the root mounting portion comprises a reinforced resin composite material.33. A wrbine assembly according to claim 32.. wherein the reinforced resin composite material comprises hminaied layers of fibrous reinforcement material, :34, A turbine assembly according to claim 32 or 33, wherein at least some of the laminated layers of fibrous reinforcement material extend c.ontinuousy out from the root mounting portion of the turbine blade into a main body portion of the turbine blade outboard of the root mounting portion.35. A turbine assembly according to any preceding claim, wherein the wail comprises a plurality of ho!es spaced apart from each other along a width of the wall, wherein the turbine assemhiy comprises a plurality of mounting assemblies, each mounting assenthiy including a peg passing through a respective one of the plurality of holes.36, .A turbine assembly accordin.g to claim 35, wherein a plurality of pegs located within a respective plurality of' holes each engage a common damping member.37. A turbine assembly according to any preceding claim, wherein the turbine member is coupled to a rotatable hub, or is a rotatable huh or a part of a rotatable hub.38. A turbine comprising one or more turbine blades, wherein the or each turbine blade is coupled to a turbine member by a turbine assembly according to any preceding claim.39. A turbine according to claim 38. wherein the turbine is a water-driven turbine or an aindriven turbine.40. A kit of parts for a turbine assembly, the kit comprising a turbine blade root mounting portion and a mounting assembly; wherein the root mounting portion has a wail and a hole extending through a thickness of the wall; wherein the mounting assembly comprises a peg and a clamping member; wherein the peg is adapted to extend through the bole and comprises first and second opposed bearing surfaces, wherein the first bearing surihee is adapted to engage a clamping surface of the clamping member and the second bearing surface is adapted to engage an engagement surface of the hole; wherein the peg is adapted to he coupled to a retaining member located on 1.6 an opposite side of the wail to the clamping member with the clamping member and the retaining member respectively coupled to opposite end portions of the peg 41. .A kit according to claim 40, wherein the root mounting portion is integrally formed with or adapted to be attached to a main body of a turbine blade, 42. A kit according to claim 40 or 41, thither comprising a turbine member, wherein the root mounting portion is adapted to engage the turbine member, wherein the peg is adapted to urge the root mounting portion into engagement with the turbine member and to pre-4oad the root immnting portion in compression 43, A kit according to any of claims 40 to 42, farther comprising a retaining member adapted to he located on an opposite side of the wall to the clamping member.44. A kit according to claim 43. wherein the retaining member is adapted to transmit a force to the peg in a direction towards the turbine member.45. A method for assembling a turbine assembly, the method comprising the steps of: a, Providing a clamping member coupled to a turbine member; b. Positioning a root mounttng portion of a turbine blade with respect to the turbine member, the root inountng portion having a wall and a hole extending through a thickness of the wall, the hole being partially defined by an engagement surface facing away from a root end of the root mounting portion; c. Inserting a peg through the hole, the peg having a. first bearing surface and an opposed second bearing surface; d. Bringing the first bearing surface of the peg into engagement with a clamping surface of the clamping mcgr her and bringing the second bearing surface of the peg into engagement with the engagement surface of the hole.; e. Securing the peg using a retaining member located on an opposite side of the wall to the clamping member. 1*